Geocoding Interstate and Highway exits

[RobertScheitlin__GISP]

All,

   I am looking for best practice for setting up my locator to handle interstate and Highway exit numbers, i.e "I-20 @ exit 465" I currently have a composite locator that is a Point Single Address and Lot and then it goes to my US Streets with City, State and Zip. And Help or suggestions would be appreciated. I am willing to create any reference data that I might need if my centerline data for the interstate and Highways is not the route to go.

[JoeBorgione]

All,

   I am looking for best practice for setting up my locator to handle interstate and Highway exit numbers, i.e "I-20 @ exit 465" I currently have a composite locator that is a Point Single Address and Lot and then it goes to my US Streets with City, State and Zip. And Help or suggestions would be appreciated. I am willing to create any reference data that I might need if my centerline data for the interstate and Highways is not the route to go.

I don't know about best practice, but this is what I have done in the past:

Freeways in urban areas:  I address them just like the local grid.  For example 4500 S I-15 SB FWY.  For my freeways, this puts the point right on the 4500 South overpass...

Freeways in rural areas: use the mile markers as the basis for your address ranges.  Give yourself enough 'room' for decimal miles.  For example, I recently took a care of a short segment of freeway that goes from MM 81 through MM 112, so the address range is 810-1120.  Address 955 is at mile post 95.5 etc.

Mile Posts; I'm lucky that I can get good point data for mileposts, so I use them as a point feature class like MM 293 I-15 SB FWY  or MM 9 HWY 201  etc

Exits I do the same thing:  Exit 293 I-15 SB FWY or Exit 293 I-15 NB FWY.  For exits, I take the location where the off ramp diverges from the main flow.

On ramps/Off ramps can be ranged 1-3, 2-4 if you need to.  That gets confusing for people other than gis-geocode people.  I work in 9-1-1 dispatch and it's a really tough sell for dispatchers to imagine four houses along an on ramp with houses 1 and 3 on one side and 2 and 4 on the other....

If you don't have a special need to address range freeways, I'd say stick to point references for everything.  You get a little leeway when it comes to locations along freeways.

Hope this isn't rambling too much and you find it helpful!